Adhoc 36" Oven in Lake District, UK

[fornax hominus]

This fall my oven will be 10 years old. It’s a member of the family now , but I can relate to your issues with curing and all .
i ended up worrying about trapped moisture and put in a top vent on the outside of the parged exterior , esp. as it took me another year to get my personal blacksmith to make the roof and until then I only had a tarp.
I took the handle fornax hominus ...oven man ....it took up my life for a year and I thought it would never get done!
The top of my dome is a real hack job , odd bits and wedges, it sure ain’t no oil painting.. but 500+ firings on it’s doing just fine.
My arch cracked on the first fire and , well , that crack is still there and I don’t worry about it.
Go forth , enjoy your oven , be prepared to put on a few pounds doing so ...
cheers Tim

[MickyPizza]

Thanks brad mole
SableSprings

Next stop is in fact the Vermicrete layer but the weather here in the Lake District is so damn up and down at the minute. We had glorious spring like sunshine in Feb (got LOADS done) then it was snow/sleet/rain/cold over weekend... to a glorious and warm day yesterday... to finish my final slate work. Today - pishing down and windy!!! Pah!!

As for the curing.... yesterday, whilst damp on the outside of blanket, it remained cool to the touch. I THINK the brickwork, depsite the sooting etc, is good. Its possibly because Im using a a lot of soft wood and whatevers at hand to get the fires going.

Can see the finish line. More pics to upload now...

[MickyPizza]

This fall my oven will be 10 years old. It’s a member of the family now , but I can relate to your issues with curing and all .
i ended up worrying about trapped moisture and put in a top vent on the outside of the parged exterior , esp. as it took me another year to get my personal blacksmith to make the roof and until then I only had a tarp.
I took the handle fornax hominus ...oven man ....it took up my life for a year and I thought it would never get done!
The top of my dome is a real hack job , odd bits and wedges, it sure ain’t no oil painting.. but 500+ firings on it’s doing just fine.
My arch cracked on the first fire and , well , that crack is still there and I don’t worry about it.
Go forth , enjoy your oven , be prepared to put on a few pounds doing so ...
cheers Tim

Great post Tim. That pic in the snow!!! Wow! Theres a man that is dedicated to his pizzas!!! And the fact yours was damp still AND cracked and yet its done SO many working days - very impressive and thanks for the encouragement. I personally think yours looks bloody good from what I can see!
One of my best pals lives over Ottawa direction. Frank Morris - he came to the UK in the 80/90s as an NHL draft and was a bit of a hockey superstar over here. Great great guy. I keep meaning to go over and visit, He moved back over about 3 years ago after over 20 yrs in Scotland.
And judging by your pic, you can see why Ice Hockey is so popular!! (and very hot ovens!!)

[MickyPizza]

Although Ive had some hot HOT temps already (not sure If I posted as such) I bought another bag of hardwood logs yesterday and took advantage of a dry day to get the thing fired up. Blanket (two of em) is ON, and STAYING ON, so any external cracks...Im past caring (curing!?) now! Hit the magical 900F (was up to 493C) nice. Whilst doing so I finally finished the right hand top part of the slate front.

What Ive done here is, made a squareish shape here for the chimney etc. Because Im basically making this up as I go along, my thinking is - get an aperture roughly straight and squared up so that something...whatever it is.. will fit in there for whatever chimney I end up fitting. Nearly at the finish line. Just the vermicrete mix then then the concrete rendering over the top with pieces of slate pushing into for decorative purposes.

Any advice from you knowledgable lot regarding how can I can make this work for the chimney and attachment etc would be appreciated

[fornax hominus]

Great post Tim. That pic in the snow!!! Wow! Theres a man that is dedicated to his pizzas!!! And the fact yours was damp still AND cracked and yet its done SO many working days - very impressive and thanks for the encouragement. I personally think yours looks bloody good from what I can see!
One of my best pals lives over Ottawa direction. Frank Morris - he came to the UK in the 80/90s as an NHL draft and was a bit of a hockey superstar over here. Great great guy. I keep meaning to go over and visit, He moved back over about 3 years ago after over 20 yrs in Scotland.
And judging by your pic, you can see why Ice Hockey is so popular!! (and very hot ovens!!)

Haha! I do draw a line in the snow at -20c , not too cold for the oven , just the operator!
I don’t think it was moisture that cracked my arch , more likely thermal expansion.. I did excavate a chunk of mortar from my first pizza, but since then nothing .
i recently had rodents trying to move into the thick layer or vermiculite I have over the blanket .. they were drilling in through vermicrete around the chimney I have been parking with Portland mortar and jamming copper mesh into any crevice that they might exploit. But it did take 10 years for them to find the weak point .
I see by your oven that just as with my fieldstone work you get all the stone you think you will need and then you do that several times ! And I appreciate you not telling me the daffodils are out!

[MickyPizza]

Haha! I do draw a line in the snow at -20c , not too cold for the oven , just the operator!
I don’t think it was moisture that cracked my arch , more likely thermal expansion.. I did excavate a chunk of mortar from my first pizza, but since then nothing .
i recently had rodents trying to move into the thick layer or vermiculite I have over the blanket .. they were drilling in through vermicrete around the chimney I have been parking with Portland mortar and jamming copper mesh into any crevice that they might exploit. But it did take 10 years for them to find the weak point .
I see by your oven that just as with my fieldstone work you get all the stone you think you will need and then you do that several times ! And I appreciate you not telling me the daffodils are out!

"The daffodils ARE out" Tunneling Rodents and heaps of deep snow...you have plenty of extra problems there eh!

[MickyPizza]

ARGHHHH!!! Why does no-one tell you just how much of an utter PIG it is to get the vermicrete done!!! Ouch! 15 mins to mix a barrow (or less) at a 10:1 ratio, mixing the cement and water first. Each barrow load = 3 hrs to apply!!!! It took me many many attempts to realise a much wetter mix works better. I started off just smearing it with my, gloved, hands but with a wetter mix the small trowel entered the fray. So so time consuming. I must have spent 15 hours or more on this stage already.
It built up, layer after layer, hour after hour (sounds like a lyric from Gangstas Paradise) ....in fact - the number of songs played on 'repeat' in my head during this stage has drove me crazy!! - "build me up, buttercup" and (Bomfunk MC's - Freestyler) "yeahh - straight from the top of ma dome" and "Verm, verm, verm-iculite" (No-No-notorious) fecksake!!!
And it was then that the optional thing became a necessity - my hearth wasn't deep enough at the back to have enough thickness of insulating concrete and render!!! I always knew it and hoped I could get away with it. Though of all manner of ways to do it. In the end, becoming the 'builder by trade' that I have! I figured it out and got an inpromptu frame made and concreted inside an hour. Sorted

Also - got a door too. I expected to pay a local blacksmith around £100-150 . He asked for £30 'and a pizza' - needs a paint and some modifications but I'm not complaining!!

[david s]

I’ve found that a 10:1 mix is about as lean as you can go whilst still having the mix workable. Also a handful of powdered clay for every 10 litres of vermiculite helps enormously to give the mix more stickiness. The correct amount of water in the mix is vital. Generally 3 litres for every 10 litres of vermiculite is about right, but this varies depending on the grade used. A fine grade needs more water. I always mix the dry ingredients in the barrow first then add about 1/3 of the water, mix well with a spade. A mixer tends to enrage the grains and the stuff sticks to the sides and blades too much, whereas a spade and barrow allow you to mix gently, see and feel the mix. Continue folding the 2nd third of the water in and break up any lumps that form with the back of the spade. Finally add the last third of the water and use the same technique to fold it in. The correct amount of water is when it just starts to pool in the bottom of the barrow, too much and it will wash the cement off the grains resulting in an inconsistent mix. I’ve been using this method for more than 0 years and have hand mixed tons of the stuff, works pretty well for me. It’s essential to wear rubber gloves if the mix is applied by hand, or you’ll be sorry. Start from the bottom creating a ledge on top to take the next row. Hope this helps.

[MickyPizza]

I’ve found that a 10:1 mix is about as lean as you can go whilst still having the mix workable. Also a handful of powdered clay for every 10 litres of vermiculite helps enormously to give the mix more stickiness. The correct amount of water in the mix is vital. Generally 3 litres for every 10 litres of vermiculite is about right, but this varies depending on the grade used. A fine grade needs more water. I always mix the dry ingredients in the barrow first then add about 1/3 of the water, mix well with a spade. A mixer tends to enrage the grains and the stuff sticks to the sides and blades too much, whereas a spade and barrow allow you to mix gently, see and feel the mix. Continue folding the 2nd third of the water in and break up any lumps that form with the back of the spade. Finally add the last third of the water and use the same technique to fold it in. The correct amount of water is when it just starts to pool in the bottom of the barrow, too much and it will wash the cement off the grains resulting in an inconsistent mix. I’ve been using this method for more than 0 years and have hand mixed tons of the stuff, works pretty well for me. It’s essential to wear rubber gloves if the mix is applied by hand, or you’ll be sorry. Start from the bottom creating a ledge on top to take the next row. Hope this helps.

Thanks for the tips david s - wish I'd seen them earlier haha. The 'ledge' at the bottom is probably the best way to go. Also fell foul of the leaks in gloves thing too!!!

But... tonight, after ANOTHER 5 hours of doing it, I FINSHED!!! Now I need to think about how to attach my chimney pipe!? Then its a cement render with slate pushed into it. Is that just standard cement and sand?

[UtahBeehiver]

You really need to let the vcrete dry out well before you do your render coat. This type of insulation contains a tremendous amount of water and when if sublimates to steam during the curing process the volume of the water vapor increase by a factor of 1500 that of liquid water. This will crack you insulation and/or render. It may take several weeks or a month for the vcrete to dry.

[MickyPizza]

You really need to let the vcrete dry out well before you do your render coat. This type of insulation contains a tremendous amount of water and when if sublimates to steam during the curing process the volume of the water vapor increase by a factor of 1500 that of liquid water. This will crack you insulation and/or render. It may take several weeks or a month for the vcrete to dry.

Thanks for the advice!! I have it fully cured already and have hit the top temps. I will focus on the Chimney situation, and the rest of the building work around the rest of my plot. will start cooking in it this weekend, and the repeated fires should dry it out ready for an end of April rendering coat. Don't wanna see the final finish crack after all this work!!!

[UtahBeehiver]

Even though the oven is cured, if you heat from cooling will still turn the water to steam and pressure will build up between the dome and the vcrete and possibly crack the vcrete too. So go slow. David S suggest placing a sheet of plastic over the dome while heating and if you see condensate there is still water in the vcrete. You see steam, you are heating too fast too quick.

[MickyPizza]

Listening to your advice, but also taking my own instinctive judgement into account, I fired oven back up to temp, but with a view to leaving it after an hour at full gas and not adding anymore wood to it.

I cooked my first proper pizzas in it (I've done two others so far) but again this was first day dough, so results (in my opinion) were ok I suppose.

During the whole heating process the dome was cool to the touch. Surely a good sign that the insulation, expecially the blankets, are working really well. I covered it back up, next morning outside of vcrete dome was warmish, and some moisture, but no steam, no cracks or anything.

[MickyPizza]

Over the rest of last weekend, I set about sorting out my chimney. My pal sold me a section of 6 inch flue pipe for £20 and I just had to figure out how to attach it. Once again, Im adhoc, making it up as I go along here. I had seen a post on here about cuts to the pipe to create bendable flanges. Great idea!

When building the opening arch i'd deliberately left a squareish aperture to make it easier down the line when it came to sort of chimney situation. I used an old metal sign that I found in the garage made of road sign type metal and thickness. Thin enough to cut easily, thick enough to be strong for the baseplate. I fashioned a makeshift baseplate in sections and bolted it together. I drilled through it and through the thick piece of slate I'd spanned across the front of the dome. However it wasn't quite enough to stop it moving fore-aft, even with some pieces of slate mortared in over the arch on top of that baseplate section. So, I got a good sized piece of slate put on top to span the front edge
That chimney is moving NOWHERE now! But not only that, it caps off the slate work and makes a neat looking finish I'd thought. I cleaned up some of the mortar splashes etc off the slate and took a couple of pictures.

[MickyPizza]

Pizza Time!!!! Sat and Monday I got the oven in full blown pizza mode. Heated for an hour to hour and a half and started cooking. All came out amazing on the 2-3 day old dough!

Waiting a few weeks or til May before I do the concrete rendering with slate, as recommended by UtahBeehiver

But, after two or three good, long, hot firings - no cracks to the dome, internally looks good, Outside stays very very cool. At most it has got to 50c on the outside - after many hours post cooking.